Leeds striker Marcus Antonsson had cancelled out Pritchard's opener before the break and after Nelson Oliveira had put Norwich back in front in extra time, Chris Wood struck in the 109th minute as the game ended 2-2 after two hours.

The hosts, who had used all three substitutes, played the whole of extra time with 10 men after defender Lewie Coyle limped off injured in the 90th minute.

But they forced the shoot-out and, despite Kalvin Phillips seeing his effort saved by John Ruddy and Matt Grimes firing over, Vieira held his nerve to clinch Garry Monk's side a place in the quarter-finals.

There was a minute's applause prior to kick-off for former Leeds goalkeeper Gary Sprake, who died last week aged 71

The Welshman made over 500 appearances for the club under Don Revie in the 1960s and 70s and his tribute was warmly observed.

Sprake would have approved when Silvestri prevented Norwich from taking the lead in the opening seconds as the Italian guessed right and smothered Naismith's shot.

Leeds were not so lucky the next time Norwich swept forward down the left as the unmarked Pritchard stooped low to head home in the 14th minute from Brady's cross.

Norwich were full of running, slick and accurate in possession and Leeds were in danger of falling further behind.

Brady's curling effort was tipped over by Silvestri and from the corner Oliveira's goalbound first-time shot was blocked by Gaetano Berardi, making only his second appearance of the season.

Leeds defender Kyle Bartley clearly handled Alex Mowatt's corner into the net, but there was nothing wrong when they equalised in the 43rd minute.

Pritchard curled a free-kick just wide and Antonsson's thumping drive was pushed over the crossbar by Norwich goalkeeper Ruddy before the interval.

Ruddy pulled off an even better save soon after the restart to keep out Doukara's thumping header from Mowatt's corner and Silvestri was alert to palm away Oliveira's shot after the Portuguese had skirted round Bartley.